The present invention relates to improvements in apparatus for sorting or classifying objects according to their lengths. Objects which can be classified in the apparatus of the present invention can include pills, tablets and/or a variety of other objects having an elongated shape and a lenticular, oval, circular, elongated rod-shaped or other outline.
Commonly owned German Offenlegungsschrift No. 34 27 535 discloses a classifying apparatus wherein a magazine contains a supply of randomly intermixed satisfactory and defective objects. The objects are discharged into a composite conveyor comprising two successive vibratory chutes which deliver the objects to a first classifying apparatus. Objects having satisfactory widths and/or thicknesses are discharged onto a chute which delivers them onto the upper reach of an endless belt conveyor or into the circumferential groove of a wheel-shaped conveyor. Successive objects on the belt conveyor or in the groove of the wheel-shaped conveyor are monitored by an optical detector, and signals which are generated by the detector are used to expel (segregate) objects of unsatisfactory lengths.
U.S. Pat. No. 3,455,444 discloses an apparatus for classifying cucumbers according to their lengths. Successive cucumbers are advanced by two mutually inclined neighboring endless belt conveyors into the range of an optoelectrical detector which generates signals for deflection of cucumbers having different lengths in different directions. The arrangement is such that all very long cucumbers are deflected in one direction, all shorter cucumbers are deflected in another direction, and the shortest cucumbers are permitted or caused to advance along their original path. A drawback of the patented apparatus is that it cannot be used for proper classification of relatively small objects because it does not ensure adequate orientation of successive objects and reliable retention of objects in a preselected position and orientation during testing. Furthermore, the conveyors which are used in the patented apparatus tend to accumulate dust and other foreign matter which can adversely influence the accuracy of the testing operation if the testing operation involves monitoring radiation which is reflected by the conveyor or conveyors.